Mail security is of increasing concern to many individuals and businesses. To prevent theft of checks, such as U.S. social security checks, dividend checks, etc., or to prevent loss or disclosure of confidential business information, there is often an urgent need for individuals or businesses to be alerted when mail delivery occurs. A signal system is particularly desirable for those locations where it is difficult or impossible to view the mailbox. However, with a timely, reliable signal, prompt action can be taken to pick up a mail delivery. For those with a long or physically difficult trip to the mailbox, such a system is also particularly desirable.
In addition, security of property is also of increasing concern to many individuals or businesses. For instance, in many rural areas, it would be desirable to provide a warning signal when fence gates or building doors are opened, so that prompt action can be taken to secure the areas against theft of animals, machinery, or other property.
A number of devices for providing mail arrival signals have been identified. A search of the patent literature has disclosed various patents, as follows:
Canadian Patent No. 507,682, issued Nov. 30, 1954 to Bordner, describes an early battery powered signal unit for mailboxes. The unit evidently required periodic battery replacement The apparatus was quite bulky, and required numerous separate attachments for both the batteries and the transmitter. The upwardly extending antenna was also an easy target for vandals. Additionally, Bordner uses a pin-type activation switch, which is prone to adverse effects from wear and weather.
U.S. Pat. No. 3,611,333, issued Oct. 5, 1971 to Conigliaro, illustrates a battery powered signal transmitter and a remote receiver for use in indicating mail deposit The device evidently operates in the frequency range used by garage door openers. Thus, it is often subject to spurious triggering. A pin-type switch is also utilized, which is prone to failure due to adverse effects just described above.
U.S. Pat. No. 3,707,260, issued Dec. 26, 1972 to Gelineau, Sr. et al., illustrates a mailbox which includes a mechanism responsive to opening of the door to trigger a transmitter, which sends a signal to a receiver to provide notice of mail delivery. Gelineau's alarm system is not suitable for attachment to existing mailboxes; rather, this design is easily or economically practiced only by initial fabrication of a mailbox to incorporate the described actuator and switch mechanism.
U.S Pat. No. 4,287,514, issued Sept. 1, 1981 to Wartman et al., illustrates a signalling device for attachment to the bottom of an existing mailbox. The device is activated by the opening of the door against a pin-type switch, which is prone to failure. Also, attachment of the device in the field requires careful location of the switch.
U.S. Pat. No. 4,520,350, issued May 28, 1985 to Huang, illustrates a mailbox design which includes an end switch to detect door opening, and a transmitter to send a signal to a remote receiver and alarm system. The design is only appropriate for incorporation into newly manufactured boxes, and does not easily lend itself to retrofit of currently installed mailboxes. Also, the upwardly mounted antenna requires a mailbox roof penetration, subjecting it to potential moisture infiltration, as well as providing a convenient target for vandals.
U.S. Pat. No. 4,794,377, issued Dec. 27, 1988 to Benages, illustrates a mail signal system which is triggered by a photodiode Benages' device also suffers from the vertically mounted roof penetrating antenna. Also, this apparatus is not appropriate for existing mailboxes.
Another attempt at developing a mail alarm system is described in an installation manual for an electronic mail detector which was developed by Creative Technologies, Inc., in 1987. That device utilizes two infrared sensors. When the sensors are covered by arriving mail, an alarm signal is generated. However, the device is prone to rapidly depleting batteries, since the IR sensors check for mail approximately every five minutes.
Other types of alarm devices have been discovered in the patent literature, as follows:
U.S. Pat. No. 3,603,952, issued to Smith on Sept. 7, 1971, describes an oil spill sensor for remote locations The device utilizes solar cells for energy replenishment, and a radio telemetry circuit for sending an alarm signal.
U.S. Pat. No. 3,980,996, issued to Greenspan et al. on Sept. 14, 1976, describes a simple charging device for a battery powered radio-frequency alarm transmitter.
It is significant that the prior art identified above does not address a variety of details disclosed herein which are necessary to facilitate quick, inexpensive installation to existing mailboxes. In fact, many of the devices disclosed in the prior art references are considerably more complex than I consider desirable, especially from an installer or user's viewpoint. Neither have the prior art devices addressed radio frequency transmitter or receiving details which accomplish reliable operation over relatively long distances. Furthermore, none of the devices have included details such as a musical alarm in order to provide a less intrusive alarm. Finally, the prior art mailbox alarm systems of which we are aware do not disclose use of solar cells for replenishment of batteries I consider this item to be of paramount importance. The lack of solar cell designs which provide for a self-contained, internally rechargeable power supply in mailbox signal systems has heretofore been a significant drawback. Simple battery powered mail signal systems, without provisions for recharge, have allowed inadvertent security failures in prior art devices, particularly at those times when batteries fail.